Bending of the fetal head in the first period of the birth process is determined according to the obkash law. The pressure created as a result of the contraction of the muscles of the uterine fundus is directed along the back of the fetus and directs the head towards the small pelvis. The short side of Obkash's shoulder is the nape of the neck, and the long side is the forehead. When the muscles of the uterus contract and press on the spine, the long shoulder of the fetus rises up, the fetal head bends, the nape of the head falls down due to the short shoulder pulling down.